Abstract: A medical system contains a first implantable device and a second implantable device. Each implantable device contains a communication unit configured to transmit an ultrasonic signal to the communication unit of another implantable device of the medical system. The first implantable device is configured to periodically transmit a broadcast message to at least the second implantable device using the communication unit of the first implantable device.

Abstract: A medical system contains a first implantable device and a second implantable device. Each implantable device contains a communication unit configured to transmit an ultrasonic signal to the communication unit of another implantable device of the medical system. The first implantable device is configured to periodically transmit a broadcast message to at least the second implantable device using the communication unit of the first implantable device.

Abstract: A pacing system, which is particularly suitable for implantable leadless pacemakers, applies passively-balanced voltage-based pacing pulses, and periodically performs capture verification (evoked response detection) by following a pacing pulse with a current-based active balancing pulse, and then measuring any evoked response provoked by the pacing pulse. The active balancing pulse reduces residual charge on the electrodes used for pulsing, and thereby reduces polarization artifacts that could obscure measurement of the evoked response at the electrodes. The amplitude and pulse width of the active balancing current pulse are defined by measurements made in a few preceding pulses. The pacemaker preferably detects indicia of cardiac contractility, and performs capture verification only when contractility indicates that the patient is physically inactive and emotionally stable.

Abstract: Electrical stimulation of a target (e.g., nervous tissue) is performed, wherein balance phases are automatically determined, and at least one of the electrodes is indirectly monitored during therapy delivery. The stimulation system is further configured to generate correction currents when a voltage accumulated at associated double layer capacitances crosses pre-defined thresholds so as to reduce or cancel the accumulated voltages without therapy interruption. A finer automatic determination of balance phases permits minimizing the stimulus artifact for evoked response sensing. Closed-loop neurostimulation may be performed based on such evoked responses.

Abstract: A pacing system, which is particularly suitable for implantable leadless pacemakers, applies passively-balanced voltage-based pacing pulses, and periodically performs capture verification (evoked response detection) by following a pacing pulse with a current-based active balancing pulse, and then measuring any evoked response provoked by the pacing pulse. The active balancing pulse reduces residual charge on the electrodes used for pulsing, and thereby reduces polarization artifacts that could obscure measurement of the evoked response at the electrodes. The amplitude and pulse width of the active balancing current pulse are defined by measurements made in a few preceding pulses. The pacemaker preferably detects indicia of cardiac contractility, and performs capture verification only when contractility indicates that the patient is physically inactive and emotionally stable.

Abstract: Electrical stimulation of a target (e.g., nervous tissue) is performed, wherein balance phases are automatically determined, and at least one of the electrodes is indirectly monitored during therapy delivery. The stimulation system is further configured to generate correction currents when a voltage accumulated at associated double layer capacitances crosses pre-defined thresholds so as to reduce or cancel the accumulated voltages without therapy interruption. A finer automatic determination of balance phases permits minimizing the stimulus artifact for evoked response sensing. Closed-loop neurostimulation may be performed based on such evoked responses.

Abstract: An implantable medical device (IMD) may include multiple power supply circuits and an electrostimulation therapy output circuit configured to, in response to a control signal specifying an electrostimulation therapy, controllably connect any one or more of the first or second power supply circuits to any one or more of a first electrostimulation output node or a second electrostimulation output node to deliver an electrostimulation. In an embodiment, the IMD may include an electrostimulation therapy return circuit configured to establish a return path for the electrostimulation delivered via one or more of the first electrostimulation output node or the second electrostimulation output node.

Abstract: An apparatus comprises a therapy circuit that provides a neural stimulation current, an impedance measurement circuit that measures a value of impedance at the output of the therapy circuit, a supply voltage generating circuit that provides an adjustable supply voltage value to the therapy circuit including a first supply voltage value when in a first mode, and a control circuit communicatively coupled to the therapy circuit, the impedance measuring circuit, and the supply voltage generating circuit. The control circuit, upon receiving an indication to exit the first mode, initiates an impedance measurement by the impedance measurement circuit, determines the second supply voltage value using the impedance measurement, and initiates a change from the first supply voltage value to the second supply voltage value. The second supply voltage value is sufficient to operate the therapy circuit and to provide a specified load current value to the measured impedance.

Abstract: An intra-body ultrasonic signal can be converted into a first electrical signal, a local oscillator signal can be generated in an implantable system. The first electrical signal and the local oscillator signal can be mixed in an implantable system, such as to generate a demodulated signal, processed, such as using a filter. The filtered, demodulated signal can be further processed, such as implantably determining a peak amplitude of the first portion of the demodulated signal received from the filter over a time interval, implantably generating a dynamic tracking threshold that starts at an amplitude proportional the first portion of the demodulated signal and exponentially decays over a time interval, and determining a noise floor in the absence of a received intra-body ultrasonic signal and implantably comparing the peak amplitude and the tracking threshold and generate the digital output based on the difference.

Abstract: An apparatus comprises an electrostimulation energy storage capacitor, a circuit path communicatively coupled to the electrostimulation energy storage capacitor and configured to provide quasi-constant current neural stimulation through a load from the electrostimulation energy storage capacitor, a current measuring circuit communicatively coupled to the circuit path and configured to obtain a measure of quasi-constant current delivered to the load, and a control circuit communicatively coupled to the current measuring circuit, wherein the control circuit is configured to initiate adjustment of the voltage level of the storage capacitor for a subsequent delivery of quasi-constant current according to a comparison of the measured load current to a specified load current value.

Abstract: An apparatus comprises a cardiac signal sensing circuit configured to sense an electrical cardiac signal from at least one of an atrium or ventricle of a heart of a subject, a therapy circuit configured to provide electrical pacing therapy and electrical autonomic neural modulation therapy to the subject, and a control circuit. The control circuit is configured to initiate delivery of the autonomic modulation neural therapy, and the control circuit includes a signal detection circuit configured to detect delivery of the autonomic neural modulation therapy in the sensed cardiac signal. The control circuit is configured to change, in response to detecting the delivery, a sensitivity of the cardiac signal sensing circuit during delivery of the autonomic neural modulation therapy.

Abstract: An implantable medical device (IMD) may include multiple power supply circuits and an electrostimulation therapy output circuit configured to, in response to a control signal specifying an electrostimulation therapy, controllably connect any one or more of the first or second power supply circuits to any one or more of a first electrostimulation output node or a second electrostimulation output node to deliver an electrostimulation. In an embodiment, the IMD may include an electrostimulation therapy return circuit configured to establish a return path for the electrostimulation delivered via one or more of the first electrostimulation output node or the second electrostimulation output node.

Abstract: An apparatus comprises an electrostimulation energy storage capacitor, a circuit path that provides pacing stimulation from the capacitor through the load, a constant current neural stimulation circuit that is switchable into the circuit path to provide neural stimulation through the load and switchable out of the circuit path to provide the pacing stimulation through the load, and a control circuit configured to selectively enable delivery of the pacing stimulation or the constant current neural stimulation.

Abstract: An apparatus comprises a cardiac signal sensing circuit configured to sense an electrical cardiac signal from at least one of an atrium or ventricle of a heart of a subject, a therapy circuit configured to provide electrical pacing therapy and electrical autonomic neural modulation therapy to the subject, and a control circuit. The control circuit is configured to initiate delivery of the autonomic modulation neural therapy, and the control circuit includes a signal detection circuit configured to detect delivery of the autonomic neural modulation therapy in the sensed cardiac signal. The control circuit is configured to change, in response to detecting the delivery, a sensitivity of the cardiac signal sensing circuit during delivery of the autonomic neural modulation therapy.

Abstract: An apparatus comprises a therapy circuit that provides a neural stimulation current, an impedance measurement circuit that measures a value of impedance at the output of the therapy circuit, a supply voltage generating circuit that provides an adjustable supply voltage value to the therapy circuit including a first supply voltage value when in a first mode, and a control circuit communicatively coupled to the therapy circuit, the impedance measuring circuit, and the supply voltage generating circuit. The control circuit, upon receiving an indication to exit the first mode, initiates an impedance measurement by the impedance measurement circuit, determines the second supply voltage value using the impedance measurement, and initiates a change from the first supply voltage value to the second supply voltage value. The second supply voltage value is sufficient to operate the therapy circuit and to provide a specified load current value to the measured impedance.

Abstract: An intra-body ultrasonic signal can be converted into a first electrical signal, a local oscillator signal can be generated in an implantable system. The first electrical signal and the local oscillator signal can be mixed in an implantable system, such as to generate a demodulated signal, processed, such as using a filter. The filtered, demodulated signal can be further processed, such as implantably determining a peak amplitude of the first portion of the demodulated signal received from the filter over a time interval, implantably generating a dynamic tracking threshold that starts at an amplitude proportional the first portion of the demodulated signal and exponentially decays over a time interval, and determining a noise floor in the absence of a received intra-body ultrasonic signal and implantably comparing the peak amplitude and the tracking threshold and generate the digital output based on the difference.

Abstract: An intra-body ultrasonic signal can be converted into a first electrical signal, a local oscillator signal can be generated in an implantable system. The first electrical signal and the local oscillator signal can be mixed in an implantable system, such as to generate a demodulated signal, processed, such as using a filter. The filtered, demodulated signal can be further processed, such as implantably determining a peak amplitude of the first portion of the demodulated signal received from the filter over a time interval, implantably generating a dynamic tracking threshold that starts at an amplitude proportional the first portion of the demodulated signal and exponentially decays over a time interval, and determining a noise floor in the absence of a received intra-body ultrasonic signal and implantably comparing the peak amplitude and the tracking threshold and generate the digital output based on the difference.

Abstract: An apparatus comprises an electrostimulation energy storage capacitor, a circuit path communicatively coupled to the electrostimulation energy storage capacitor and configured to provide quasi-constant current neural stimulation through a load from the electrostimulation energy storage capacitor, a current measuring circuit communicatively coupled to the circuit path and configured to obtain a measure of quasi-constant current delivered to the load, and a control circuit communicatively coupled to the current measuring circuit, wherein the control circuit is configured to initiate adjustment of the voltage level of the storage capacitor for a subsequent delivery of quasi-constant current according to a comparison of the measured load current to a specified load current value.

Abstract: An apparatus comprises an electrostimulation energy storage capacitor, a circuit path that provides pacing stimulation from the capacitor through the load, a constant current neural stimulation circuit that is switchable into the circuit path to provide neural stimulation through the load and switchable out of the circuit path to provide the pacing stimulation through the load, and a control circuit configured to selectively enable delivery of the pacing stimulation or the constant current neural stimulation.

Abstract: A system and method for in situ trimming of oscillators in a pair of implantable medical devices is provided. Each frequency over a range of oscillator trim frequencies for an initiating implantable medical device is selected and a plurality of commands are sent via an acoustic transducer in situ over the frequency selected. Each frequency over a range of oscillator trim frequencies for a responding implantable medical device is selected and a response to each of the commands received is sent via an acoustic transducer in situ over the frequency selected. The responses received by the initiating implantable medical device are evaluated and a combination of the oscillator trim frequencies for both implantable medical devices that together exhibit a strongest acoustic wave is identified. Oscillators in both implantable medical devices are trimmed to the oscillator trim frequencies in the combination identified.